At a holographic "old-timers" baseball game, Matt Hunter and several other Net Force Explorers are thrilled to see Babe Ruth swing for the fences. But when Ruth does his famous routine of pointing to the stands, four people dressed in 30s-style outfits stand up and open fire with Tommy guns!Even virtual bullets can kill you. Matt and his friends know that these "virtual vandals" must be stopped. But the stadium stunt is just the beginning. And even the teens of the Net Force might not be able to stop them next time!